Methods: Male and female BALB/c mice were sensitized and subsequently challenged with aerosolized ovalbumin (OVA) on days 17-21 for serum, bronchoalveolar lavage fluid (BALF), and lung tissue collection, and challenged for an additional 5 days for airway hyper-responsiveness (AHR).
Results: As compared to saline, OVA challenged mice demonstrated increased serum OVA-IgE, AHR, levels of type 2 cytokines (IL-4, IL-5, IL-13), and cellular influx of eosinophils, B cells, dendritic cells, T cells, and ILC2. Sex differences were demonstrated such that female mice had increased serum OVA-specific IgE, lung nitric oxide levels, and AHR as compared to males. As compared to male mice, dendritic cells were decreased in BALF and B cells were increased in the BALF and lung tissues of OVA challenged females. Female OVA challenged mice also demonstrated lower frequency of ILC2 in BALF, yet increased frequency in whole lung tissue. There was a significant increase in the levels of IL-5 and IL-13 produced ex vivo by IL-33 stimulated, isolated lung ILC2 from female saline and OVA challenged mice as compared to males.
Conclusions: Taken together, the study highlights a potential sex-specific difference in ILC2 localization and activation in experimental allergic asthma.